Aircraft: B737
Phase of flight: Climb
Anomaly: Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence

When we departed we knew the weather was south of the New York area. Before departure we were told to expect at least 15 miles in-trail spacing. Immediately after departure we were given a series of S turns east and west and restricted to 17;000 FT and 250 KTS for an extended period of time due to weather south. As we were handed off to Washington Center we were given a climb to FL280 and also told to expect moderate chop in the climb. The Captain elected to keep the flight attendants seated. I also began cooling the cabin down. Approaching approximately 80 to 90 miles north of VILLS Intersection we detected a line of weather and knew we would need to deviate. We also were also experiencing continuous light to moderate chop at this time. We elected to go east even though this was the downwind side of the weather due to another area of heavy weather west of VILLS. We were given a climb to FL300 and by this time within 80 miles and were beginning to experience light to moderate turbulence. We were told that it would be a minute before we could turn but the Captain told them we needed an immediate turn do to the turbulence as we started to experience serious disruptions in pitch and roll. We began the turn to the south-east and ATC gave a further climb to FL320. As we were turning we entered an area of moderate to severe turbulence. The autopilot disengaged as it would not hold heading or altitude. I was pilot flying and was totally focused on aircraft pitch; power and keeping the right side up. This period of turbulence lasted 10 to 15 minutes. We experienced serious updrafts and downdrafts and over shot our altitude by approximately 600 FT. We informed ATC that it was impossible to maintain altitude in these conditions and were given further climb to FL340. At no time did we come within 40 miles of the heaviest depiction of weather of the radar. As a note the winds out of the southwest were around 145 KTS. We eventually leveled at ATC assigned FL350 for a period as we did not want to much higher as the ability to hold airspeed was a factor. We also did not want to descend back down to more turbulent air. We were still experiencing moderate turbulence as we were paralleling the track from VILLS to SBY. As we got south of SBY the turbulence abated to continuous light-moderate chop. We then were able to continue out climb to our filed altitude of 380. I would like to commend the Captain on his decisive coordination with ATC to get us away from the weather and helping me by giving continuous inputs on engine performance and backup on airspeed and aircraft performance. Also by seating the flight attendants early and having them stow the carts saved some serious injury. We were somewhat concerned that after we had reported this severe turbulence that ATC was still willing to allow aircraft to deviate into that area of turbulence. As we had no ACARS; we immediately reported this to Dispatch as soon as possible. We also entered this event in the logbook. At no time did we feel that aircraft load limitations were exceeded or structural integrity was compromised. Overall through teamwork and preemptive action we were able to avoid any injuries although we did have some very frightened but appreciative passengers. A B737-800 encountered severe turbulence at FL350 near SBY.